Expansible metal sheets

ABSTRACT

923,777. Metal sheet. CONCH INTERNATIONAL METHANE Ltd. Nov. 21, 1961, No. 41535/61. Class 20 (2). [Also in Groups XXII and XXVIII] Expansible metal sheet, i.e. sheet which when fully restrained and subjected to low temperatures will not suffer any stress exceeding its elastic limit, comprises a plurality of pan-shaped modular sections 4 arranged side by side and end to end and a plurality of conical or pyramidal corner metal members 7 welded together along their edges 10 (see Group XXII). Stainless steel, aluminium or aluminium alloy materials are used. U.S.A. Specification 2,971,667 is referred to.

Nov. 2, 1965 E. ARMSTRONG EXPANSIBLE METAL SHEETS Filed NOV. 6, 1962 Inventor A Home y:

United States Patent 3,215,301 EXPANSIBLE METAL SHEETS Edward Armstrong, Darlington, England, assignor to Conch International Methane Limited, Nassau, Ballamas, a Bahamian company Filed Nov. 6, 1962, Ser. No. 235,671 Claims priority, application Great Britain, Nov. 21, 1961, 41,535/ 61 6 Claims. (Cl. 220-) This invention concerns a metal sheet which when fully restrained and subjected to low temperatures will not suffer any stress exceeding its elastic limit. Such metal sheet is hereinafter called expansible metal sheet. The invention also concerns a container suitable for storage of a liquid gas or a mixture of liquid gases, in which one or more walls consist of such a metal sheet.

It is known to store a liquid gas or a mixture of liquid gases in a container fabricated of thin metal walls supported externally. However, use of such a container is complicated by need to relieve it of stresses produced by expansion and contraction of the metal wall or Walls with changes in temperature. The problem of expansion and contraction of the metal wall or walls become particularly acute at temperature normally encountered in the handling of very low boiling point liquefied gases, such as liquefied natural gas or nitrogen, because the differences between the liquid gas temperatures and ambient temperature are very great. Furthermore, if such a container is partially filled with a liquid gas or a mixture of liquid gases, a large temperature gradient can exist in the column of gas above the liquid level, which will induce additional stresses in the walls of the container. Unless these stresses are relieved, they can cause the container to fail.

In United States of America patent specification No. 2,971,166, there is disclosed a container suitable for storage of a liquid gas or a mixture of liquid gases having one or more walls produced from a metal sheet that is expansible for self-adjustment without change in overall dimensions. The container there disclosed is in the shape of a polyhedron completely enclosed by walls, in which at least one wall is produced from a metal sheet comprising a plurality of rectangular pan-shaped modular sections arranged in side-by-side and end-to-end relationship joined together along the tops of adjacent edges. The container is provided with inlet and outlet means. When such a container is subjected to changes in temperature, the joined edges are sufiiciently flexible to permit each pan to act as a diaphragm, thereby enabling the wall or walls produced from said metal sheet to withstand changes in temperature without changing their overall dimensions. The edges of the pan-shaped sections are preferably joined together by welding.

Although a container produced according to the abovementioned United States of America patent specification is satisfactory for many purposes, it has been found that if the tops of adjacent edges of the pan-shaped sections are joined together by welding, the resultant metal sheet is not expansible along the resulting long, straight, continuous welded seams.

The present invention provides expansible metal sheet comprising a plurality of quadrilateral pan-shaped modulaotr sections with rounded corners arranged in side-byside and end-to-end relationship welded together along the tops of adjacent straight edges, in which each space defined by four adjacent rounded corners is completed by a further metal member welded to the tops of the edges of said four rounded corners. In such metal sheet, the welded edges of the pans are interrupted by the further metal members and are therefore expansible.

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The pan-shaped section can be produced from stainless steels, and other metals or alloys possessing a desired structural strength. Where the metal sheet comprised of the pan-shaped sections is used as a wall or walls of a container suitable for storage of a liquid gas or a mixture of liquid gases having low boiling points (for example liquid natural gas having a boiling point of 250 F. at atmospheric pressure), the pan-shaped sections are preferably produced from metals such as aluminium, alloys of aluminium or stainless steels. The pan-shaped sections can be formed from the desired metal or alloy by known methods; for example by pressing. Preferably, they are rectangular.

The degree of flexibility required of a metal sheet of the invention is an important factor in deciding the number of pan-shaped sections required to form a given area, and the size of each of said sections. Generally, for a given pan thickness, the larger the number of pans used to form a given area, the greater will be the degree of flexibility attained.

In a metal sheet of the invention, metal members used to complete spaces defined by four adjacent rounded corners of the quadrilateral pan-shaped modular sections are any metal members that can be welded to the tops of the edges of said four corners. Preferably, the metal members are conical or pyramidal in shape or are panshaped. The aforesaid metal members in a metal sheet of the invention need not all be of the same shape; for example, they can consist of any member chosen from conical, pyramidal and pan-shaped members.

A metal sheet of the invention can be used as one or more walls of a container suitable for storage of a liquid gas or a mixture of liquid gases. In producing such a container, the outer pan-shaped sections of a side of a metal sheet of the invention can be inwardly bent to define a corner of the container; and a second metal sheet of the invention can be arranged with pan-shaped sections in end-to-end relationship with the bent pan-shaped sections of the first metal sheet, and then welded to the first metal sheet along the tops of adjacent straight sides, each space defined by four adjacent rounded corners of the panshaped sections being completed by a further metal member Welded to the tops of the edges of said four corners.

The invention is now further illustrated by reference to the accompanying drawings, in which:

FIGURE 1 is a perspective view of a corner of a container having walls produced from metal sheets of the invention;

FIGURE 2 is a perspective view of a part of a metal sheet of the invention in which a space defined by four adjacent rounded corners of four rectangular pan-shaped modular sections of metal is completed by a pyramidal metal member welded to the tops of the edges of said four corners;

FIGURE 3 is a perspective view of a part of a metal sheet of the invention in which a space defined by four adjacent rounded corners of four rectangular pan-shaped modular sections of metal is completed by a pan-shaped metal member welded to the tops of the edges of said four corners; and

FIGURE 4 is a diagrammatic elevational view of a weld joining together two rectangular pan-shaped modular sections of metal in a metal sheet of the invention.

In FIGURE 1, metal walls 1, 2 and 3 consisting of metal sheets of the invention are joined together to define a corner of a container suitable for storage of a liquid gas or a mixture of liquid gases. Each of said Walls comprises a plurality of rectangular pan-shaped modular sections 4 with smoothly outwardly rounded corners 5 arranged in side-by-side and end-to-end relationship, except that pan-shaped sections 6 common to tWo or three walls and which form the corners of the container are inwardly bent as shown. Each space defined by four adjacent rounded corners 5 is completed by a pan-shaped metal member 7. Although not shown, the pan-shaped sections 4 and 6 are welded together along the tops of adjacent straight edges; and the pan-shaped metal members 7 are welded to the tops of the edges of the four adjacent rounded corners.

In FIGURES 2 and 3, a pyrimidal metal member 8 and a pan-shaped metal member 9 respectively complete the space defined by four adjacent rounded corners 5 of the pan-shaped sections 4. The metal members are welded to the tops of the edges 10 of the rounded corners 5.

In FIGURE 4, the edges 10 of two pan-shaped metal sections 4 are joined together by a seam Weld 11 and then sealed by an argon arc seal weld 12.

Containers of this invention will normally be supported by a thermally insulating floor and thermally insulating side walls capable of carrying the liquid load for which the container is destined.

I claim:

1. Expansible metal sheet comprising a plurality of rectangular pan-shaped modular sections with smoothly outwardly continuously curving rounded corners arranged in side-by-side and end-to-end relationship and defining spaces between each four adjacent corners, which sections are welded together along the tops of adjacent straight edges, and in each of the spaces, generally concave metal members welded to the tops of the edges of the four adjacent rounded corners so as to completely and impermeably fill the space, the radius of the curvature of said rounded corners being many times greater than the thickness of the sheet material, so that thermal expansion or contraction of the straight edges of the pans only slightly changes the curvature of said arcuate edges along the weld line without producing concentrated stresses at any one localized region of the weld.

2. A concave metal sheet as claimed in claim 1 in which the metal members are pyramidal in shape.

3. A metal sheet as claimed in claim 1 in Which the sections and metal members are joined by seam welds and sealed by argon arc seal welds.

4. A container suitable for the storage of liquid gas comprising a thermally insulating floor and thermally insulating side Walls, an inner, liquid-tight container Within said walls and floor, said liquid-tight container having metal walls in which at least one of the metal walls consists of an expansible thin metal sheet comprising a plurality of quadrilateral pan-shaped modular sections with smooth, outwardly rounded corners arranged in side-byside and end-to-end relationship and defining spaces between each four adjacent corners, which sections are Welded together along the tops of adjacent straight edges, and in each of the spaces, generally concave metal members welded to the tops of the edges of the four adjacent rounded corners, the bottoms of the respective pan-shaped sections resting against and supported by said thermally insulated floor and walls, the radius of curvature of said rounded corners being many times greater than the thickness of the sheet material, so that thermal expansion or contraction of the straight quadrilateral edges of the pans only slightly changes the curvature of said arcuate edges along the weld line Without producing concentrated stresses at any one localized region of the weld.

5. Expansible metal sheet comprising a plurality of quadrilateral modular sections, each section comprising a pan having a bottom and four upstanding sides terminating in a rim, the rim of each pan being a quadrilateral figure having two sides and tWo ends, each two sides being joined by a smoothly outwardly rounded continuously curved corner to two adjacent ends, said pans being arranged in side-by-side and end-to-end relationship with the rims of adjacent pans welded together to form gas and liquid-tight seams, leaving a space at each corner due to the corners being rounded; and in each corner a concave sheet metal member with its edges welded to the curved edges of the corners to impermeably fill each said space; the welded seam between each said member and the curved rim portion to which it is joined defining a figure with four concave sides which are inwardly curved toward the center, the radius of curvature of said rounded corners being many times greater than the thickness of the sheet material, so that thermal expansion or contraction of the edges of the pans only slightly changes the curvature of said arcuate edges along the Weld line without producing concentrated stresses at any one localized region of the weld.

6. A metal sheet as claimed in claim 5, said concave sheet metal members being generally pyramidal in shape, with the apex of each pyramid extending in the same perpendicular direction as the bottoms of the pans to which they are joined.

References Cited by the Examiner THERON E. CONDON, Primary Examiner.

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1. EXPANSIBLE METAL SHEET COMPRISING A PLURALITY OF RECTANGULAR PAN-SHAPED MODULAR SECTIONS WITH SMOOTHLY OUTWARDLY CONTINUOUSLY CURVING ROUNDED CORNERS ARRANGED IN SIDE-BY-SIDE AND END-TO-END RELATIONSHIP AND DEFINING SPACES BETWEEN EACH FOUR ADJACNET CORNERS, WHICH SECTIONS ARE WELDED TOGETHER ALONG THE TOPS OF ADJACENT STRAIGHT EDGES, AND IN EACH OF THE SAPCES, GENERALLY CONCAVE METAL MEMBERS WELDED TO THE TOPS OF THE EDGES OF THE FOUR ADJACENT ROUNDED CORNERS SO AS TO COMPLETELY AND IMPERMEABLY FILL THE SPACE, THE RADIUS OF THE CURVATURE OF SAID ROUNDED CORNERS BEING MANY TIMES GREATER THAN THE THICKNESS OF THE SHEET MATERIAL, SO THAT THERMAL EXPANSION OR CONTRACTION OF THE STRAIGHT EDGES OF THE PANS ONLY SLIGHTLY CHANGES THE CURVATURE OF SAID ARCUATE EDGES ALONG THE WELD LINE WITHOUT PRODUCING CONCENTRATED STRESSES AT ANY ONE LOCALIZED REGION OF THE WELD. 